First, let’s clarify the concept of dynamic‑range value. For example, a dynamic range of 120 dB means the illuminance ratio between the brightest and dimmest areas distinguishable by the camera is 1 000 000 : 1, namely \(10^6:1\).

\(10^6:1\) equals 120 dB. The industry‑standard formula for wide‑dynamic‑range ratio is:

\(\boldsymbol{dB = 20\log_{10}(\text{Illuminance of brightest area [lx]} / \text{Illuminance of dimmest area [lx]})}\)

Calculation example: \(20\log_{10}(1\,000\,000/1)=20 \times 6 = 120\ \mathrm{dB}\)

While comparing the differences between IMX334 and IMX678, we notice IMX678 adopts a distinctive HDR technology known as Clear HDR.

The widely‑used HDR technology we have encountered is DOL HDR (Digital‑Overlap High Dynamic Range). Taking advantage of the rolling electronic shutter, DOL HDR interleaves exposure and readout to achieve “quasi‑simultaneous” exposure.

The image sensor first captures a short‑exposure frame for bright regions, then a long‑exposure frame for dark regions. The two frames are overlapped and fused to generate the HDR output.

However, a slight time offset exists between the two frames. When capturing fast‑moving subjects, motion artifacts such as blurred edges or color shifts may appear on moving parts. Moreover, DOL‑based HDR fusion is generally processed on the ISP, which consumes main‑chip computing resources.

In contrast, Clear HDR works as follows: the image sensor captures two frames concurrently — a low‑gain frame for bright areas and a high‑gain frame for dark areas, then performs image overlapping and fusion.

Since both frames are acquired simultaneously, artifact‑free images without color distortion can be obtained even for fast‑moving objects. Therefore, Clear HDR is highly suitable for applications targeting high‑speed subjects such as traffic surveillance and dashcams, especially for tunnel‑transition scenarios.

Differences between DOL HDR and Clear HDR

1. Under DOL HDR: the sensor captures two frames sequentially, one long‑exposure frame and one short‑exposure frame.
2. Under Clear HDR: the sensor captures two frames simultaneously, one low‑gain frame for bright areas and one high‑gain frame for dark areas.

Per Sony’s official statement: “The output images shall be fused by the camera to produce the final image. IMX585 can perform on‑sensor fusion when Clear HDR is enabled.”

Excerpt from the IMX678 datasheet regarding STARVIS 2: 

STARVIS 2 is a registered trademark or trademark of Sony Group Corporation or its affiliates. The STARVIS 2 is back-illuminated pixel technology used in CMOS image sensors for security camera applications. It features a sensitivity of 2000 mV or more per 1 µm2 (color product, when imaging with a 706 cd/m2 light source, F5.6 in 1 s accumulation equivalent). It also has a wide dynamic range (AD 12 bit)of more than 8 dB compared to STARVIS for the same pixel size in a single exposure, and achieves high picture quality in the visible light and near infrared light regions.

In short, IMX678 delivers 8 dB higher dynamic range compared with IMX334.

IMX334 is gradually phasing out of production. System designers can leverage the strengths of the STARVIS 2‑grade IMX678 sensor with Clear HDR when paired with a proper ISP.